Usually, metal wood number 1 drivers made of titanium and its alloys has thin (1 mm to 2 mm) top, bottom and side walls, and a relatively thick face (2.5 to 3.5 mm). This is due to weight limits of 170 grams to 210 grams, and strength factors to hold up against the forces of the golf ball impacting on the face. To form the top and bottom/side parts, usually the materials need to have less metal memory (softer and not to bounce back in the press forming process), and commercially pure titanium (CP grade) sheet is used, although titanium alloys such as Ti-6 Al/4 Va and beta alloy (T:-15-3-3-3) can be used with more costly processing. Fairway woods (Nos. 3, 4, 5, 6, 7, 8 and 9) have a less restrictive weight limit (200 grams to 250 grams) and thicker (2 mm to 3 mm) top and bottom/side members can be used.